Denmark's northern port of Frederikshavn is not waiting for the rest of the world. It has launched a green revolution to become, within seven years, the first city ever powered solely by renewable energy.

Nestled between green rolling hills and the Kattegat sea facing Sweden, this former naval base home to 25,000 residents wants to be a showcase for clean energy technology and serve as a model for other cities.

"We have set our goal - by 2015 to be the first city in the world to run on alternative energy," Frederikshavn mayor Erik Soerensen said.

The goal was born out of trauma when Frederikshavn was "sucked dry a decade ago by the closure of the shipyards, which left 7,000 people jobless," he said.

"At the time we decided to fight for our survival, to find innovative solutions with companies to create new opportunities and jobs. And this project is part of our survival strategy," he said.

Standing on the roof of city hall with its spectacular view of the city and port where passenger ferries link Denmark to Sweden and Norway, the mayor points to wind turbines already churning along the coast.

Wind power is expected to generate 30 per cent of the city's electricity needs.

Mikael Kau, the head of the Frederikshavn Energy City project started in 2008 by the city council, concedes that it's an "ambitious, pioneer" project that presents a "real challenge".

The city's current level of green energy is just 24 per cent.

Yet Mr Kau is convinced the transformation is possible in such a short time, and says he dreams of seeing homes, schools, businesses, administrations and vehicles get their heating, electricity and fuel from wind and solar energy, and biogas made from wastewater and agricultural waste.

"It's important for every person to assume their responsibility in the fight against global warming, in a world where the enormous consumption of fossil fuels threatens living conditions on earth," Mr Soerensen said.

Denmark has long been a pioneer in the green movement.

The small island of Samsoe, located in the Kattegat Sea, is already entirely self-sufficient for its electricity, 100 per cent of which is generated by wind turbines, while 75 per cent of its heating comes from solar panels and biomass.

But the Frederikshavn project is on a much larger scale.

Businesses, led by state-run power group Dong Energy, "have already signed on to the project and want to invest, which is crucial for its success," Mr Kau said.

The business sector's investments in the project are estimated at between 1.0 and 1.5 billion kroner (€134 to €201 million).

"Frederikshavn as a 'green city' will provide opportunities for new environmental technology and jobs," said the mayor.

Things started moving in 2006 when Danish energy experts selected Frederikshavn as the ideal location to "start an experimental laboratory and show other cities around the world that it is possible to transform consumption of fossil fuels into 100 per cent renewable energy in just a few years with existing technology," the mayor said.

City officials have since played host to a long line of foreign dignitaries, such as Mikhail Gorbachev, Bill Clinton and Al Gore.

The steady flow of dire climate reports have only confirmed authorities' resolve. "Something had to be done and we couldn't wait for the whole world to act," the mayor said.

The next step was to win over public support, said Marie Halgaard Nielsen, a public liaison official on the project, since "people wonder whether it's all worth it and want to know if it will create jobs and growth."

"There are sceptics, but also visionaries who are very passionate about the project," Hans Carlsen, a 54-year-old resident, said at a recent town hall debate to promote the initiative.

Among the supporters was Grethe Nielsen, a mother of three. "It's a good idea, a necessary one that opens our eyes to other sources of energy than oil - which will run out one day," she said.

But retired heating technician Niels Andersen said "everything will depend on Copenhagen's political willingness to lift the roadblocks that could endanger the success of the project".

For Flemming Soerensen, director of the nearby Strandby heating plant that has 640 solar panels turned towards the sky, a key roadblock is Danish car taxes which he feels must be cut.

The Danish government has so far refused to reduce taxes on hybrid cars, which are about 20,000 kroner (€2,685) more expensive than petrol cars.

"It's hard to ask people to change cars and pay more. Danish car taxes, which are among the highest in Europe, don't incite motorists to drive green cars," he said.

Yet Mr Soerensen "wants to believe in the project".

"We can succeed if we want and if we get outside help," he stressed.

Denmark's first biofuels pump station is due to open in Frederikshavn in September.